Microdisk structures and other microcavities are able to confine light at a high efficiency by repeated total reflection of the light at interfaces, making it possible to achieve high interactions between matter and light. Potential applications include microlasers capable of lasing at ultralow thresholds, optical signal processing, integrated optics, and high-sensitivity sensors such as biosensors.
As microdisk-forming materials, organic substances provide a number of advantages over inorganic substances. For example, organic substances can be doped with various dyes, in addition to which they are inexpensive and amenable to fabrication.
Up until now, organic microdisk fabrication has been carried out using primarily photolithography (see Non-Patent Documents 1 to 3), but the complexity of such processes has been a drawback.
By contrast, inkjet printing is simple and convenient. Moreover, because this process adds material only where needed, additional advantages are that it saves energy and provides a high degree of freedom.
However, because inkjet printing generally can discharge only low-viscosity inks having viscosities ranging from several mPa·s to several tens of mPa·s, achieving a high polymer concentration within the ink is a challenge. Hence, one drawback is that only thin films having thicknesses of up to about several hundred nm can be created.
This explains the absence to date of any instances of organic microdisk fabrication using the inkjet printing process.